But the federal government and consumer groups questioned the math behind that conclusion.

The state's comparison looks at the average monthly cost of each insurer's standard "silver" plan to be offered on the exchange versus the average monthly cost of a hypothetical plan ($293) offered today with similar benefits.

Under that scenario, monthly premiums would jump as much as 59 percent for Sunshine State Health Plans ($464) and as little as 8 percent for Humana Medical Plan ($315), according to the Florida Office of Insurance Regulation.

But these figures come with at least two significant caveats. First, the plans that will be offered on the exchange must offer better benefits than the ones many people have today. That makes it impossible to make direct comparisons to existing plans.

Secondly, the increase doesn't take into account the federal tax subsidies that are expected to help millions of Floridians — those with incomes up to four times the poverty level — purchase coverage.

A consumer advocacy group, Florida CHAIN, called it a "desperate, irresponsible, and meaningless 'comparison'."

"Although the form and rate review process is ongoing, we have released this information to help the public and our state policymakers understand the full extent of federal health care reform and its imminent impact on our state," Florida Insurance Commissioner Kevin McCarty said in a statement.

McCarty's statement notes that a number of changes are driving the increases, including the requirement that health coverage be offered to everyone, regardless of pre-existing medical conditions, and the limitation on how much a person's age can affect his health plan costs.

Eleven insurers will offer plans on Florida's exchange, which is scheduled to begin Oct. 1. Most Americans must have health insurance next year or face federal fines.

Americans who can't get affordable insurance through their employer may turn to the online exchanges – also called marketplaces – to shop for coverage.

In 2012, Floridians with individual coverage paid an average of $243 in monthly premiums. In a second comparison, state regulators note those costs would rise for customers of every insurer, on average around 39 percent. They include:

Aetna Life Insurance Company: $296

Blue Cross Blue Shield of Florida: $361

Cigna: $377

Coventry Health Care of Florida: $343

Florida Health Care Plan: $324

Health First Insurance Company: $360

Health Options Inc.: $350

Humana: $278

Molina Healthcare of Florida: $412

Preferred Medical Plan: $331

Sunshine State Health Plan: $362

For more details on the rates, consumers can go to http://www.floir.com/siteDocuments/Avg_Costs_PPACA.pdf